1. Field of the Invention
The present invention relates to an auto focus control apparatus and a continuous auto focus control method, and more particularly, to an auto focus control apparatus and a continuous auto focus control method that can improve wobbling by skipping a frame corresponding to the time when a lens moves according to pre-scan.
2. Description of the Related Art
Cameras mounted in mobile devices such as smartphones have been gradually developed to have high specifications and high functions. Important one of them is a continuous AF (C-AF) function. In order to minimize an AF speed and improve high resolution video quality such as FHD (full HD), employment of the C-AF function is increased and improvement of performance thereof becomes essential.
Describing a conventional AF process with reference to FIG. 7A, movement of a subject is determined (S10). When it is determined that the subject is moved, pre-scan is performed as a substantial AF process (S30). At this time, during the pre-scan, a focus lens alternately moves in a specific direction or in the forward and reverse directions of the specific direction to detect a scan direction and continuously moves in the scan direction to detect a peak point so that a focal value in each position of the focus lens is calculated. This process is called the pre-scan.
That is, a process of moving the focus lens forward or backward is needed during the pre-scan. In this case, there is a difference in definition of an image due to the movement of the focus lens, and this difference in the definition is shown on a preview or a video as it is. This phenomenon is called screen splashing or screen wobbling.
Wobbling causes deterioration of quality of the preview. Particularly, in the videos, such image is stored as it is, thus becoming a factor of deteriorating image quality of the videos.
As shown in FIG. 7B, in the prior art, since a pre-scan interval of a sensor frame is displayed on a preview frame as it is, wobbling occurs in this interval.